We report a case of primary clear-cell sarcoma (CCS) in the mediastinum. In October 2011, a 63-year-old man was admitted to our hospital for surgical resection. The tumor was completely excised by video-assisted thoracoscopic surgery. The tumor was well encapsulated and did not invade the pleura. Histological examination led to a final diagnosis of primary CCS in the mediastinum. The patient remains alive without evidence of recurrence at 15 months after surgery.